Endoscope Insertion Portion

ABSTRACT

An endoscope insertion portion of the invention comprises: a distal end portion; first image pickup means for obtaining a first observation image, the first image pickup means being disposed to the distal end portion; second image pickup means for obtaining a second observation image, the second image pickup means being disposed to the distal end portion; a first object optical system for condensing photographing light incident on the first image pickup means, the first object optical system being located in the distal end portion; a second object optical system for condensing photographing light incident on the second image pickup means, the second object optical system being located in the distal end portion; and a plurality of illumination optical systems for irradiating light to a subject, the plurality of illumination optical systems being located in the distal end portion in a manner sandwiching each of the first object optical system and the second object optical system. The endoscope insertion portion thus can show enough of good observation performance by distributing a plurality of image pickup means with necessary amount of illumination light.

TECHNICAL FIELD

The present invention relates to an endoscope insertion portion of anendoscope having a plurality of observation optical systems.

BACKGROUND ART

Conventionally, endoscopes have been widely used in the medical fieldand the like. With an endoscope, for example, internal organs in a bodycavity can be observed by inserting an elongated insertion portion intothe body cavity, and various treatments can be performed using atreatment instrument inserted into a treatment instrument insertionchannel as necessary. At a distal end of the insertion portion, abending portion is provided. By operating an operation portion of theendoscope, observing direction of an observation window at a distal endportion can be changed.

In general, an endoscope is provided with an air/water feeding nozzlefor cleaning for a case where body fluid or the like adheres on an outersurface of the objective optical system of the endoscope to disturb theobservation when the endoscope is inserted into the body cavity. Theouter surface of the objective optical system of the endoscope can besecured of a clean observation field of view with, for example, acleaning liquid spouted out or air sprayed from the air/water feedingnozzle.

For example, an endoscope having a plurality of objective opticalsystems is proposed as described in Japanese unexamined patentpublication No. 06-154155. This endoscope has a plurality of imagepickup units, wherein the plurality of objective optical systems and anaperture of an air/water feeding nozzle are located at a distal end ofan insertion portion to line up on a generally straight line. In orderto obtain images by the image pickup units, the endoscope has twoillumination optical systems for irradiating illumination light into thebody cavity where almost no natural light enters.

Further, in recent years, there have been endoscopes that can perform,in addition to normal light observation for picking up an image in thebody cavity which is generally the same as in naked-eye observation byirradiating mainly white light or RGB light by the frame sequentialmethod into the body cavity, special light observation such as, forexample, fluorescent light observation, that can specify a lesion regionexisting in a diseased part which is difficult to be diagnosed by thenormal light observation, by irradiating light having a specificwavelength band into the body cavity to pick up an image of the diseasedpart.

However, in an endoscope described in Japanese unexamined patentpublication No. 06-154155, there is a problem that a region to beinspected cannot be iiradiated with enough amount of illumination light,due to absence of consideration for cleanability by liquid or gas froman air/water feeding nozzle for cleaning outer surfaces of twoillumination optical systems when the outer surfaces of the twoillumination optical systems are adhered with mucous membrane, blood,filth or the like in the body cavity. The endoscope has another problemthat, in a large intestine, for example, which is a body cavity, the twoillumination optical systems are covered by folds of the intestine,thereby blocking the illumination light from reaching the region to beinspected.

Moreover, in the case of, for example, fluorescent light observation asa special light observation to be performed in the body cavity, since alesion region in a diseased part emits only a small amount offluorescent light, second illumination means used for the special lightobservation is required to receive the fluorescent light emitted fromthe lesion region in as large an amount as possible. Therefore, it ispossible that an object optical system used in fluorescent lightobservation is rendered incapable of showing enough observationperformance of, for example, a fluorescent light image pickup unit forspecial light observation, when an outer surface of the object opticalsystem is adhered with mucous membrane, blood, filth or the like presentin an optical axis direction thereof, or when the observation field ofview is obstructed by folds of a body cavity, particularly, anintestine.

Incidentally, among special light observations to be performed in a bodycavity, in the case of, for example, the fluorescent light observation,when there is a lesion region in a diseased part, which emits only asmall amount of fluorescent light, it is necessary to receive thefluorescent light emitted from the lesion region in as large an amountas possible. Therefore, in fluorescent light observation, it isnecessary to irradiate the lesion region with larger amount ofillumination light than in normal light observation.

Thus, in an endoscope having a plurality of image pickup units, it isnecessary that light having a specific wavelength band that isirradiated into a body cavity from the illumination optical system influorescent light observation is more surely irradiated to the lesionregion of the diseased part than white light or RGB light by the framesequential method that is irradiated into the body cavity from anillumination optical system in normal light observation.

However, in the endoscope of the Japanese unexamined patent publicationNo. 06-154155, no specific description is made about disposition of theillumination optical system used for special light observation such asfluorescent light observation, and there have been problems as mentionedabove.

Thus, in view of the above-described circumstances, an object of thepresent invention is to provide an endoscope insertion portion of anendoscope capable of showing enough of good observation performance bydistributing a plurality of image pickup means with necessary amount ofillumination light, in particular, ensuring good amount of observationlight to be incident on an image pickup unit for special light, which isrequired to be received in as large an amount as possible, as well asshowing enough observation performance of an image pickup unit forspecial light.

DISCLOSURE OF THE INVENTION Means for Solving the Problem

To achieve the above-described objects, an endoscope insertion portionof the invention comprises: a distal end portion; first image pickupmeans for obtaining a first observation image, the first image pickupmeans being disposed to the distal end portion; second image pickupmeans for obtaining a second observation image, the second image pickupmeans being disposed to the distal end portion; a first object opticalsystem for condensing photographing light incident on the first imagepickup means, the first object optical system being located in thedistal end portion; a second object optical system for condensingphotographing light incident on the second image pickup means, thesecond object optical system being located in the distal end portion;and a plurality of illumination optical systems for irradiating light toa subject, the plurality of illumination optical systems being locatedin the distal end portion in a manner sandwiching each of the firstobject optical system and the second object optical system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustrative view schematically showing an endoscopesystem.

FIG. 2 is a perspective view showing a distal end cover of an endoscope.

FIG. 3 is a perspective view showing the distal end cover of theendoscope.

FIG. 4 is a plan view of the distal end cover as viewed from the front.

FIG. 5 is a section view of the distal end portion and a bending portioncut along A-A line of FIG. 4.

FIG. 6 is a section view of the distal end portion cut along B-B line ofFIG. 4.

FIG. 7 is a section view showing a diverging part of an air/waterfeeding duct.

FIG. 8 is a section view of the distal end portion cut along C-C line ofFIG. 4.

FIG. 9 is a section view of the distal end portion cut along D-D line ofFIG. 4.

FIG. 10 is a section view of the distal end portion cut along E-E lineof FIG. 5.

FIG. 11 is a section view of the bending portion cut along F-F line ofFIG. 5.

FIG. 12 is a plan view of the distal end cover as viewed from the front.

FIG. 13 is a plan view of the distal end cover as viewed from the front.

FIG. 14 is a plan view of the distal end cover as viewed from the front.

FIG. 15 is a plan view of a distal end cover in a modification exampleas viewed from the front.

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment

Referring to the drawings, a first embodiment of the present inventionis described below.

First, based on FIG. 1, configuration of an endoscope system accordingto the present embodiment is described. FIG. 1 is an illustrative viewschematically showing a configuration of the endoscope system accordingto the first embodiment of the present invention.

As shown in FIG. 1, an endoscope system 1 of the present embodimentincludes: an endoscope 2 capable of performing normal light observationand fluorescent light observation; a light source device 3 for supplyingillumination light to the endoscope 2; a processor 4 serving as a signalprocessing device for performing signal processing for the endoscope 2;a monitor 5 which is inputted with a video signal outputted from theprocessor 4 to display an endoscope image for normal observation orfluorescent light observation; an air/water feeding device 6 for feedingair and water; and a forward water-feeding device 6 a for forwardlyfeeding water.

The endoscope 2 includes: an endoscope insertion portion (hereinaftersimply referred to as insertion portion) 11 elongated to facilitateinsertion into a body cavity; an operation portion 12 connected to aproximal end of the insertion portion 11; and a universal cable 13extending from a side portion of the operation portion 12. A connector14 provided to an end portion of the universal cable 13 is detachablyconnected to the light source device 3.

The insertion portion 11 of the endoscope 2 includes: a rigid distal endportion 15 formed at a distal end of the insertion portion 11; a bendingportion 16 formed at a proximal end of the distal end portion 15; and aflexible tube portion 17 having flexibility formed from the proximal endof the bending portion 16 to the operation portion 12.

In the insertion portion 11, a light guide 21 for transmittingillumination light is inserted. The light guide 21 is inserted into theuniversal cable 13 via the operation portion 12, and has a proximal endportion 22 connected to a light guide connector not shown protrudingfrom the connector 14.

A distal end part of the light guide 21 is fixed in the distal endportion 15. Note that at the distal end part of the distal end portion15 is disposed an illumination lens 25 of an illuminating unit describedbelow which is an illumination optical system, and illumination light isradiated from the light guide 21 via the illumination lens 25. On adistal end surface of the distal end portion 15, a distal end cover 24is provided.

Note that, in the present embodiment, the light guide 21 is inserted inthe insertion portion 11, being, for example, diverged in the operationportion 12 to be split twofold in the insertion portion 11. Distal endsurfaces of the respective light guides 21 split twofold are eachlocated near rear surfaces of the two illumination lenses 25 provided onthe distal end cover 24.

Also, in the insertion portion 11 is provided a treatment instrumentchannel (also referred to as forceps channel) which is a first duct(omitted in FIG. 1) for rendering a treatment instrument such as aforceps insertable into the insertion portion 11. A distal end of thetreatment instrument channel has an aperture at a distal end surface ofthe distal end cover 24.

The treatment instrument channel diverges near the proximal end of theinsertion portion 11. One of the diverged treatment instrument channelsis inserted up to a treatment instrument insertion port not showndisposed to the operation portion 12. The other of the divergedtreatment instrument channels communicates with a suction channel inthrough the insertion portion 11 and the universal cable 13, with aproximal end being connected to an absorbing portion not shown servingas absorbing means via the connector 14.

In the distal end portion 15, two image pickup units are disposed. Inthe present embodiment, there are incorporated a normal-light-observingimage pickup unit (hereinafter referred to as normal light image pickupunit) 31A which is a first image pickup portion configuring first imagepickup means for normal light observation, and afluorescent-light-observing image pickup unit (hereinafter referred toas fluorescent light image pickup unit) 31B which is a second imagepickup portion configuring second image pickup means for specialobservation.

Note that the second image pickup portion configuring the second imagepickup means, which in the present embodiment is afluorescent-light-observing image pickup unit capable of performingfluorescent light observation which is a special observation, may be,for example, an image pickup unit for night vision observation, an imagepickup unit for infrared observation, or the like, and is not limited touse for fluorescent light observation in particular.

To the normal light image pickup unit 31A and the fluorescent lightimage pickup unit 31B, respective one ends of a signal cables 38 a, 38 bare connected. Respective other ends of the signal cables 38 a, 38 b areinserted into the operation portion 12 and the universal cable 13, andare switchably connected to a common signal cable 43 in a relay board 42provided in the connector 14.

The common signal cable 43 is connected to a processor 4 in through ascope cable 44 connected to the connector 14.

In the processor 4, there are provided driving circuits 45 a, 45 b forrespectively driving image pickup devices of the normal light imagepickup unit 31A and the fluorescent light image pickup unit 31B; asignal processing circuit 46 for performing signal processing to imagepickup signals respectively outputted from the two image pickup devicesvia the relay board 42; and a control circuit 47 for controllingoperation state of the signal processing circuit 46 or the like.

Also, the operation portion 12 of the endoscope 2 is provided withcontrol switches 48 a, 48 b; an air/water feeding button 63; a bendingoperation knob not shown; a switch not shown (also referred to astele-zoom button) for performing tele-zoom operation of the normal lightimage pickup unit 31A; a forward water-feeding button not shown; and theabove-described treatment instrument insertion port (not shown).

The control switches 48 a, 48 b are connected to the control circuit 47of the processor 4 via signal lines 49 a, 49 b, respectively. In thepresent embodiment, for example, the control switch 48 a generates asignal for switching instruction, and the control switch 48 b generates,for example, a signal for freezing instruction.

The relay board 42 performs, responsive, for example, to operation ofthe control switch 48 a, a switching operation such that, from a statewhere one of the signal cables 38 a, 38 b respectively connected to theimage pickup devices is connected to the common signal cable 43, theother signal cable is connected to the signal cable 43.

Specifically, for example, by operating the control switch 48 a, aswitching signal is outputted to the relay board 42 via a switchingsignal line 49 c which is inserted in the scope cable 44 andelectrically connected to the control circuit 47. The relay board 42connected with the switching signal line 49 c is configured such that aninput terminal for signals from the control circuit 47 is normally in L(LOW) level, with a switching control terminal pulled down, and in thisstate, the signal cable 38 a of the normal light image pickup unit 31Ais connected to the common signal cable 43. Also in an activationstarting state, the switching control terminal is in the L level. Thatis, unless a switching instruction is performed, the relay board 42 isset to a normal light observation state.

When a user operates the control switch 48 a in this state, a controlsignal is applied by which a signal from the control circuit 47 becomesH (HIGH) level at the input terminal of the relay board 42 via theswitching signal line 49 c. Then, the relay board 42 pulls up theswitching control terminal, and in this state, the signal cable 38 b ofthe fluorescent light image pickup unit 31B is connected to the commonsignal cable 43.

When the control switch 48 a is further operated, the switching controlterminal is supplied with an L level signal, and the signal cable 38 aof the normal light image pickup unit 31A is connected to the commonsignal cable 43.

With the operation of the control switch 48 a, the control circuit 47sends a control signal also to the control circuit 58 in the lightsource device 3 via the control signal line 49 d in the scope cable 44.Then, in response to the control signal, the control circuit 58 controlsto obtain a state of generating normal observation light or excitationlight for fluorescent light observation. Further, the control circuit 47controls operation state of the signal processing circuit 46 so that thesame is operated corresponding to respective image pickup devices of thenormal light image pickup unit 31A and the fluorescent light imagepickup unit 31B.

The light source device 3 includes: a lamp 51 for generating white lightincluding wavelength of the excitation light; a collimator lens 52 forbringing light of the lamps 51 into a parallel luminous flux; a rotaryfilter 53 disposed in an optical path of the collimator lens 52, andprovided in a circuit direction with an RGB filter that respectivelypass lights of wavelength bands of R (RED), G (GREEN) and B (BLUE) invisible light wavelength band (380 to 780 nm), for example; and acondensing lens 54 for condensing transmission light of the rotaryfilter 53 and radiates the light to the proximal end portion 22 of thelight guide 21.

The rotary filter 53 provided with the RGB filter is also provided, onan outside of the circuit direction, with an excitation light filter forpassing excitation light with a wavelength band shorter than that ofvisible light. The rotary filter 53 is rotatably driven by a motor 55.Further, the motor 55 is mounted to a rack 56 and can be moved in adirection orthogonal to an illumination optical axis as shown in anarrow, by means of a gear-equipped motor 57 engaging with the rack 56.

The gear-equipped motor 57 is controlled by a control circuit 58. Thecontrol circuit 58 is connected to the control circuit 47 of theprocessor 4 via the control signal line 49 d, and is operated by thecontrol switch 48 a to perform a corresponding control operation.

On the distal end portion 15, there is also located an air/water feedingnozzle 60 which is an air/water feeding portion configuring air/waterfeeding means such that a spouting port thereof faces outer surfaces ofrespective object lenses (hereinafter also referred to as observationlenses) of the normal light image pickup unit 31A and the fluorescentlight image pickup unit 31B located on the distal end cover 24.

The air/water feeding nozzle 60 is connected to an air/water feedingduct 61 whose distal end sides are joined to unite, as described below.A proximal end side of the air/water feeding duct 61 diverges into anair feeding duct 61 a and a water feeding duct 61 b.

The air feeding duct 61 a and the water feeding duct 61 b communicatingwith the air/water feeding nozzle 60 are inserted up to the connector 14of the universal cable 13, and connected to the air/water feeding device6 incorporating a pump not shown for feeding air and water.

The air feeding duct 61 a and the water feeding duct 61 b are interposedwith the above-described air/water feeding button 63 in the operationportion 12 present at a halfway of the ducts. Air and water are fed byoperating the air/water feeding button 63.

This causes the air/water feeding nozzle 60 to blow a gas such as air ora liquid such as distilled water to outer surfaces of respective objectlenses of the normal light image pickup unit 31A and the fluorescentlight image pickup unit 31B located in a spouting direction, so as toremove and clean off body fluid, accretion or the like so that imagepickup and observation field of view can be ensured in a clean state.

The insertion portion 11 is also provided inside with a forwardwater-feeding channel (omitted in FIG. 1) which is a second duct forfeeding a liquid such as distilled water to a region to be inspected inthe body cavity. A distal end of the forward water-feeding channel hasan aperture on a distal end surface of the distal end cover 24.

The forward water-feeding channel is connected to the forwardwater-feeding device 6 a, and interposed with a forward water-feedingbutton not shown disposed to the operation portion 12. When the forwardwater-feeding button is operated, a liquid such as distilled water issprayed from the distal end surface of the insertion portion 11 towardan insertion direction into the body cavity. By this, body fluid or thelike adhered to a region to be inspected in the body cavity can becleaned. Note that, as shown in FIG. 1, a cable extending from theforward water-feeding device 6 a is connected with a foot switch 6 b.Also by operating the foot switch 6 b, a user can spray a liquid such asdistilled water toward the insertion direction into the body cavity fromthe distal end surface of the insertion portion 11.

Further, the above-mentioned treatment instrument channel and theforward water-feeding channel configure an endoscope duct in the presentembodiment.

As shown in FIGS. 2 to 4, on the distal end cover 24 disposed to thedistal end portion 15 of the insertion portion 11, there are disposed:an observation lens 31 a which is a first observation optical system ofthe normal light image pickup unit 31A; an observation lens 31 b whichis a second observation optical system of the fluorescent light imagepickup unit 31B; three illumination lenses 25 a, 25 b, 25 c asillumination optical systems; an aperture portion 26 of the treatmentinstrument channel; and an aperture portion 27 of the forwardwater-feeding channel. On the distal end cover 24, the air/water feedingnozzle 60 is located such that a spouting port 60 a is oriented towardthe observation lenses 31 a, 31 b, as described above.

Note that FIGS. 2 and 3 are each a perspective view showing the distalend cover part of the endoscope, and FIG. 4 is a plan view of the distalend cover as viewed from the front. The two observation lenses 31 a, 31b are observation optical members, and the three illumination lenses 25a, 25 b, 25 c are illumination optical members.

Specifically, the observation lens 31 a as a first object optical systemis disposed at the generally center of the distal end surface of thedistal end cover 24 in a generally circle shape when the distal endportion 15 is viewed from the distal end. Further, on the distal endsurface of the distal end cover 24, the illumination lenses 25 a and 25b as first and second illumination optical systems, respectively, aredisposed in a manner sandwiching the observation lens 31 a, on right andleft sides as viewed toward the surface of FIG. 4.

On the distal end surface of the distal end cover 24, the observationlens 31 b as a second object optical system is disposed on a lower rightside of the observation lens 31 a as viewed toward the surface of FIG.4. Also, in a manner sandwiching the observation lens 31 b from upperand lower sides are disposed the illumination lens 25 a positioned onthe upper side and the illumination lens 25 c as a third illuminationoptical system positioned on the lower side. Moreover, on the distal endsurface of the distal end cover 24, there are disposed the apertureportion 27 of the forward water-feeding channel at an upper right sideof the observation lens 31 a; the air/water feeding nozzle 60 on anupper left side; the observation lens 31 b on a lower right side; andthe aperture portion 26 of the air/water feeding channel on a lower leftside, as viewed toward the surface of FIG. 4.

Note that locations of the observation lenses 31 a, 31 b, theillumination lenses 25 a to 25 c, the aperture portions 26, 27, and theair/water feeding nozzle 60 disposed on the distal end cover 24 in thepresent embodiment will be described in detail later.

Next, referring to FIGS. 5 to 11, internal configuration of the distalend part of the insertion portion 11 of the endoscope 2 of the presentembodiment is described. Note that FIG. 5 is a section view of thedistal end portion and the bending portion cut along A-A line of FIG. 4;FIG. 6 is a section view of the distal end portion cut along B-B line ofFIG. 4; FIG. 7 is a section view showing a diverging part of theair/water feeding duct; FIG. 8 is a partial section view of the distalend portion cut along C-C line of FIG. 4; FIG. 9 is a partial sectionview of the distal end portion cut along D-D line of FIG. 4; FIG. 10 isa section view of the distal end portion cut along E-E line of FIG. 5;and FIG. 11 is a section view of the bending portion cut along F-F lineof FIG. 5.

As shown in FIG. 5, in the bending portion 16 of the endoscope 2, aplurality of circular ring-shaped bending pieces 7 are rotatablyprovided in a linked manner. The bending pieces 7 each include on aninner circumferential surface four wire guards 7 a fixedly providedthereon by means such as welding. The four wire guards 7 a are fixed onan inner circumferential surface of one bending piece 7 at positionsshifted by about 90 degrees from each other about the insertion axis(see FIG. 10).

The plurality of bending pieces 7 are coated, in a manner covering outercircumferences thereof, with a bending braid 9 made of a thin wireknitted in a pipe shape. The bending braid 9 is watertightly covered byan outer covering 10, thereby forming the bending portion 16.

The outer covering 10 provides a covering over the distal end portion15, the bending portion 16, and an end portion of a distal end side ofthe flexible tube portion 17. Both outer peripheral distal end parts ofthe outer covering 10 and the flexible tube portion 17 are fixedlyadhered with a spool adhering portion 10 a at the distal end portion 15.

Also, in the insertion portion 11, four bending operation wires 8 areinserted which are bending operation means extending from the bendingportion 16 toward a proximal end thereof. Distal end parts of these fourbending operation wires 8 are respectively held and fixed, shifted byabout 90 degrees from each other about the insertion axis, by fourfixing portions 18 a (see FIG. 11, only one is shown in FIG. 5) of afixing ring 18 provided in the distal end portion 15. Proximal end sideparts of the bending operation wires 8 are insertingly provided in therespective wire guards 7 a provided to the bending pieces 7.

Note that the distal end portion 15 and each of the bending pieces 7 areconnected in a linked manner such that the bending operation wires 8held and fixed by the respective fixing portions 18 a of the fixing ring18 provided in the distal end portion 15 and inserted into therespective wire guards 7 a of the bending pieces 7 are in a generallystraight line, in a state where the insertion axis of the bendingportion 16 is in a generally straight line.

Also, the proximal end portions of the bending operation wires 8 areconnected to a bending operation mechanism not shown provided in theoperation portion 12 (see FIG. 1) and connected to the bending operationknob, so as to be alternately pulled or relaxed.

By the four bending operation wires 8 each being pulled or relaxedthrough a predetermined operation of the bending operation knob, thebending portion 16 is operated to be bent in four directions. These fourdirections are up/down and left/right four directions of an endoscopeimage photographed by each of the image pickup units 31A, 31B anddisplayed on the monitor 5 as discussed below.

Also, two of the bending operation wires 8 as a first bending operationmember configuring a first bending operation means for operating thebending portion 16 in up/down direction, and the other two of thebending operation wires 8 as a second bending operation memberconfiguring a second bending operation means for operating the bendingportion 16 in the left/right direction, respectively make pairs. Thatis, the two bending operation wires 8 respectively inserted and held inthe two wire guards 7 a in a direction corresponding to the up/downdirection of the bending pieces 7 in the bending portion 16 are thefirst bending operation means. The other two bending operation wires 8respectively inserted and held in the two wire guards 7 a in thedirections corresponding to the left/right direction in the bendingpieces 7 in the bending portion 16 are the second bending operationmeans.

In the distal end portion 15, there are disposed a columnar member 15 amade of a rigid metal and formed with a plurality of, eight in thepresent embodiment, hole portions; and a circular ring-shapedreinforcing ring 15 b fitted onto a proximal end side outercircumference portion of the columnar member 15 a. The fixing ring 18including the above-described four fixing portions 18 a is inserted andfitted on an inner circumferential side of the reinforcing ring 15 b ofthe distal end portion 15. Further, a proximal end part of thereinforcing ring 15 b is connected to a distal-most bending piece 7.

Two of the eight hole portions formed on the columnar member 15 a of thedistal end portion 15 form distal end parts of the treatment instrumentchannel 19 and the forward water-feeding channel 20. In the fiveremaining hole portions are respectively disposed the above-describednormal light image pickup unit 31A, the fluorescent light image pickupunit 31B, the air/water feeding nozzle 60, and two illumination lensunits described below.

The treatment instrument channel 19 includes the aperture portion 26having an aperture on the distal end cover 24 provided on the distal endsurface of the distal end portion 15; a generally cylindrical tubemember 19 a inserted and fitted in the hole portion of the columnarmember 15 a of the distal end portion 15; and a treatment instrumentduct 19 b made of a flexible tube, whose distal end part covers aproximal end portion of the tube member 19 a and is connected and fixedto the proximal end portion with a spool.

The treatment instrument duct 19 b is inserted in through the insertionportion 11, and has a proximal end with an aperture at the treatmentinstrument insertion port (not shown in FIG. 1) in the operation portion12, as described above.

Also, the forward water-feeding channel 20 having the aperture portion27 similarly on the distal end cover 24 includes a generally cylindricaltube member 20 a inserted and fitted in the hole portion of the columnarmember 15 a of the distal end portion 15; and a forward water-feedingduct 20 b covering the proximal end part of the tube member 20 a andhaving a distal end part connected and fixed to the proximal end partwith a spool.

The forward water-feeding duct 20 b is inserted up to the connector 14though the insertion portion 11, the operation portion 12, and theuniversal cable 13, and is connected to the forward water-feeding device6 a. Note that, as described above, the forward water-feeding duct 20 bwhich is the forward water-feeding channel 20 is interposed with theforward water-feeding button (not shown) in operation portion 12.

In the endoscope 2 of the present embodiment, the signal cable 38 a andthe signal line 38 c connected to the normal light image pickup unit 31Aare disposed at the generally center in the bending portion 16 of theinsertion portion 11 (see FIG. 10).

Thus, the signal cable 38 a and the signal line 38 c each insertedinside with a metal wire can be applied with a reduced level of bendingstress due to bending of the bending portion 16 compared to whendisposed on an outer circumferential side in the bending portion 16.That is, as the bending portion 16 is bent more, moving amount of thesignal cable 38 a and the signal line 38 c in an axis direction of theinsertion portion 11 is increased in the bending portion 16.Accordingly, the signal cable 38 a and the signal line 38 c are disposedat the generally center in the bending portion 16 in order to reduce themoving amount of the signal cable 38 a and the signal line 38 c in theaxial direction when the bending portion 16 is bent.

Further, in the bending portion 16, the two light guides 21, thetreatment instrument duct 19 b, the forward water-feeding duct 20 b, andthe air/water feeding duct 61 are disposed in a predetermined manner tosurround the signal cable 38 a and the signal line 38 c. The two lightguides 21 are covered by a flexible tube 28, and the forwardwater-feeding duct 20 b is also covered by a flexible tube. Thetreatment instrument duct 19 b and the air/water feeding duct 61 areeach a flexible tube.

Thus, the signal cable 38 a and the signal line 38 c are protectedagainst external force due to the bending of the bending portion 16.

In the endoscope 2 of the present embodiment, the bending portion 16 canbe bent in the four directions toward up/down and left/right sides on anendoscope image photographed by each of the image pickup units 31A, 31Band displayed on the monitor 5, as mentioned above. In each of thedirections toward the up/down sides, the bending portion 16 can be bentin 180 degrees, for example. In each of the directions toward theleft/right sides, the bending portion 16 can be bent in 160 degrees, forexample. In other words, the bending portion 16 of the endoscope 2 canbend to a larger extent of 180 degrees in each of the up/down directionsthan the bendable angle 160 degrees in each of the left/rightdirections.

As mentioned above, the signal cable 38 a and the signal line 38 c haveincreasing amount of movement in the axial direction of the insertionportion 11 along with the bending angle of the bending portion 16.Therefore, in the bending portion 16, at least the signal cable 38 a orthe signal line 38 c is disposed on a line linking the two wire guides 7a in left/right direction as viewed toward the surface of FIG. 10. Thisincreases durability of the signal cable 38 a or the signal line 38 c.

As shown in FIG. 6, the aperture portion 60 is a tubular member bent ina generally L shape, and has a proximal end part inserted and fitted inthe hole portion of the columnar member 15 a of the distal end portion15 such that the spouting port 60 a on the distal end side is orientedtoward outer surface sides of the respective observation lenses 31 a, 31b.

To a proximal end side of the hole portion of the columnar member 15 acorresponding to the air/water feeding nozzle 60, a distal end part ofthe tube member 62 is inserted. A proximal end part of the tube members62 is connected with the air/water feeding duct 61. Note that the tubemember 62 and the air/water feeding duct 61 are connected and fixed bymeans of a spool.

As shown in FIG. 7, the air/water feeding duct 61 has a proximal endpart connected to a diverging tube 50. The diverging tube 50 hasdivergence ends respectively connected to distal end parts of the airfeeding duct 61 a and the water feeding duct 61 b. This brings theair/water feeding duct 61 into communication with the air feeding duct61 a and the water feeding duct 61 b. Note that each of the ducts 61, 61a, 61 b and the diverging tube 50 are connected and fixed by means of aspool. Respective connecting portions and the entire periphery of thediverging tube 50 are applied, for example, with an adhesive or thelike, so that the each connecting portion is airtightly (watertightly)held.

Three of the eight hole portions formed on the columnar member 15 a ofthe distal end portion 15 are each inserted and fitted with anillumination lens unit 23 from the distal end side. Proximal end partsof these three hole portions are respectively inserted with distal endparts of the light guide 21.

As shown in FIGS. 8 and 9, the illumination lens unit 23 includes aplurality of illumination lenses 25 and a holding barrel 23 a forholding the illumination lenses 25. Note that the three illuminationlens units 23 in the present embodiment respectively include theillumination lenses 25 a, 25 b, 25 c present at the distal-most ends ofthe illumination lenses 25.

The light guide 21 has a distal end part covered with a cylindricalmember 21 a, and is coated with an outer covering 29 made of a pluralityof strings of fibers bundled together. The cylindrical member 21 a has aproximal end part connected and fixed to a tube 28 whose distal end partis fixed with a spool. The light guide 21 coated by the outer covering29 passes in through the tube 28.

Note that one of the seven hole portions of the columnar member 15 a isdisposed with the normal light observation unit 31A, including theobservation lens 31 a, which is a first observation optical system fixedby a first observation optical system fixing member as first observationoptical system fixing means such as a screw and adhesive, for example.This hole portion configures a first observation optical systemdisposition portion which is a first observation optical systemdisposition means.

Another one of the hole portions is disposed with the fluorescent lightobservation unit 31B, including the observation lens 31 b, which is asecond observation optical system fixed by a second observation opticalsystem fixing member as second observation optical system fixing means,such as a screw and adhesive, for example. This hole portion configuresa second observation optical system disposition portion which is asecond observation optical system disposition means.

Further, in other three hole portions, the three illumination lens units23, respectively including the illumination lenses 25 as first, secondand third illumination optical systems, are respectively fixed andlocated by first, second and third illumination optical system fixingmembers as first, second and third illumination optical system fixingmeans such as a screw and adhesive, for example. These three holeportions respectively configure first, second and third illuminationoptical disposition portions as first, second and third illuminationoptical disposition means.

Also, of the eight hole portions, a hole portion in which the air/waterfeeding means is located configures an air/water feeding portiondisposition portion as air/water feeding portion disposition means inwhich is fixed and located the air feeding nozzle 60 by first air/waterfeeding portion fixing means such as a screw and adhesive, for example.

Further, of the eight hole portions, a hole portion in which thetreatment instrument channel 19 which is a first endoscope duct islocated configures a first endoscope duct disposition portion as firstendoscope duct disposition means.

Also, a hole portion in which the forward water-feeding channel 20 as asecond endoscope duct is located configures a second endoscope ductdisposition portion as second endoscope duct disposition means. Thetreatment instrument channel 19 is fixed and located in one of the sevenhole portions by a first endoscope duct fixing member as first endoscopeduct fixing means such as a screw and an adhesive, for example. Theforward water-feeding channel 20 is fixed and located in one anotherhole portion by a second endoscope duct fixing member as secondendoscope duct fixing means such as a screw and adhesive, for example.

Returning to FIG. 6, the normal light image pickup unit 31A includes alens unit 32, an image pickup device 33 such as CCD (Charge CoupledDevice) and CMOS (Complementary Metal-Oxide Semiconductor), and acircuit board 34.

The lens unit 32 includes first to fourth lens groups 32A to 32D, andfirst to fourth lens barrels 32 a to 32 d. In the present embodiment,the first lens group 32A formed by four object lenses containing theobservation lens 31 a is held by the first lens barrel 32 a. The secondlens 32B formed by one object lens is held by the second lens barrel 32b. Further, the third lens group 32C formed by two object lenses is heldby the third lens barrel 32 c. Still further, the fourth lens group 32Dformed by three object lenses is held by the fourth lens barrel 32 d.

Incidentally, the second lens barrel 32 b for holding the second lens32B is a moving barrel which can advance and retreat in a photographingoptical axis direction for zooming. Note that the second lens barrel 32b is moved to advance and retreat in the photographing optical axisdirection by a driving portion serving as driving means such as, forexample, a motor and actuator not shown provided to the normal lightimage pickup unit 31A when a zooming operation lever not shown providedto the operation portion 12 is operated by a user.

The driving means for moving the second lens barrel 32 b to advance andretreat in the photographing optical axis direction is supplied with adrive-stop signal through a signal line 38 c shown in FIG. 10. Thesignal line 38 c is inserted from the normal light image pickup unit 31Aup to the operation portion 12 in through the insertion portion 11.

The image pickup device 33 is provided, on a light receiving surfaceside, with a cover lens 33 a adjacently provided on a proximal end sideof an object lens at the proximal-most end of the fourth lens barrel 32d, and outputs an electrical signal corresponding to an optical image tothe circuit board 34. The circuit board 34 includes electrical parts anda wiring pattern, photoelectrically converts an optical image from theimage pickup device 33 to an electric image signal, and then outputs theimage signal to the signal cable 38 a. Note that the circuit board 34 isconnected with a plurality of signal lines of the signal cable 38 a bymeans of soldering or the like.

The cover lens 33 a, the image pickup device 33, the circuit board 34,and a distal end part of the signal cable 38 a have respective outercircumference portions unitedly covered by an insulation sealing resinor the like, and are coated by a reinforcing circular ring portion 35 aand an insulating tube 35 b.

The signal cable 38 a transmits image signals acquired by the imagepickup device 33 and the circuit board 34 of the normal light imagepickup unit 31A to the signal processing circuit 46 of the processor 4via the relay board 42 and the signal cable 43 of the connector 14 shownin FIG. 1.

Meanwhile, like the normal light image pickup unit 31A, the fluorescentlight image pickup unit 31B includes a lens unit 32, an image pickupdevice 38 such as CCD and CMOS, and a circuit board 39.

The lens unit 36 includes first and second lens groups 36A, 36B andfirst and second lens barrels 32 a, 32 b. In the present embodiment, thefirst lens group 36A formed by seven object lenses including theobservation lens 31 b is held by the first lens barrel 36 a, and thesecond optical lens 36B is held by the second lens barrel 36 b.

The image pickup device 38 is provided, on a light receiving surfaceside, with a cover lens 40 adjacently provided on a proximal end side ofan object lens at the proximal-most end of the second lens barrel 36 b.The image pickup device 38 outputs an electrical signal of an opticalimage to the circuit board 39. The circuit board 39 has electrical partsand a wiring pattern similarly as the circuit board 34 of the normallight image pickup unit 31A, and is connected with a plurality of signallines of the signal cable 38 a by means of soldering or the like. Thecircuit board 39 photoelectrically converts an optical image from theimage pickup device 38 to an electric image signal, and then outputs theimage signal to the signal cable 38 b.

The cover lens 40, the image pickup device 33, the circuit board 34, anda distal end part of the signal cable 38 a have respective outercircumference portions unitedly covered by an insulation sealing resinor the like, and are coated by a reinforcing circular ring portion 35 aand the insulating tube 35 b.

The signal cable 38 b transmits image signals acquired by the imagepickup device 38 and the circuit board 39 of the fluorescent light imagepickup unit 31B to the signal processing circuit 46 of the processor 4via the relay board 42 and the signal cable 43 of the connector 14 shownin FIG. 1.

The above-described normal light image pickup unit 31A and thefluorescent light image pickup unit 31B are respectively inserted intopredetermined hole portions provided to the columnar member 15 a of thedistal end portion 15, and are firmly fixed thereto with a fixing membersuch as a screw along with an adhesive or the like as described above.

In the present embodiment, the observation lens 31 a provided at thedistal end of the normal light image pickup unit 31A has a lens diameter(caliber) that is larger than a lens diameter of the observation lens 31b located at the distal end of the fluorescent light image pickup unit31B.

Also, setting directions of the image pickup units 31A, 31B in thedistal end portion 15 are determined such that respective lightreceiving surfaces of the two image pickup devices 33, 38 are orthogonalto the insertion axis of the insertion portion 11, and horizontaltransfer directions and vertical transfer directions of the two imagepickup devices 33, 38 agree to each other, respectively.

Further, subject images photographed by the image pickup units 31A, 31Bare displayed on the monitor 5 (see FIG. 1). Note that up/down directionof the monitor 5 agrees with vertical transfer direction of the CCD orCMOS device of each of the image pickup devices 33, 38, and left/rightdirection of the monitor 5 agrees with horizontal transfer direction ofthe CCD or CMOS device of each of the image pickup devices 33, 38. Inother words, up/down and left/right directions of an endoscope imagephotographed by each of the image pickup units 31A, 31B agree withup/down and left/right directions of the monitor 5.

Up/down and left/right directions of the bending portion 16 of theinsertion portion 11 are determined to correspond to the up/down andleft/right directions of an endoscope image displayed on the monitor 5.That is, the four bending operation wires 8 inserted in through thebending portion 16 are pulled and relaxed by a predetermined operationof the bending operation knob provided to the operation portion 12 asdescribed above, so as to render the bending portion 16 bendable inup/down and left/right four directions corresponding to the up/down andleft/right directions of an image displayed on the monitor 5.

In other words, setting directions of the image pickup units 31A, 31B inthe distal end portion 15 are determined such that horizontal transferdirections and vertical transfer directions of the image pickup devices33, 38 respectively agree so that up/down and left/right directions ofan endoscope image displayed on the monitor 5 always agree with thosedirections of the bending operation directions of the bending portion 16even when normal light observation and fluorescent light observation areswitched from one to the other.

Thus, the user can perform bending operation of the bending portion 16in up/down and left/right directions without having a sense ofincongruity about those directions of an endoscope image displayed onthe monitor 5 when endoscope images with normal light and fluorescentlight are switched from one to the other.

Note that, in the description below, up/down direction as a firstdirection will be described as up/down direction of an endoscope imagedisplayed on the monitor 5 and up/down direction in which the bendingportion 16 is operated to be bent. Normally, the monitor 5 is installedsuch that up/down direction thereof generally agrees with plumb up/downdirection. Further, left/right direction as a second direction which isgenerally orthogonal to the up/down direction is identical to theleft/right direction of an endoscope image displayed on the monitor 5and the left/right direction in which the bending portion 16 is operatedto be bent.

Here, actions of the above-described endoscope system 1 are described.

As shown in FIG. 1, a user connects the connector 14 of the endoscope 2to the light source device 3, and further connects one end of the scopecable 44 to the connector 14 and the other end of the scope cable 44 tothe processor 4. The user also connects the air feeding duct 61 a andthe water feeding duct 61 b to the air/water feeding device 6.

Then, the user turns on power switches of the light source device 3 andthe like to bring these devices into operation state. At this time, therespective control circuits 47, 58 of the processor 4 and the lightsource device 3 are rendered capable of transmitting and receivingcontrol signals.

The relay board 42 is set to select the normal light image pickup unit31A side in activation state. Also, the control circuit 47 performs acontrol operation so that a normal light observation state is set. Thatis, the control circuit 47 sends a control signal to the control circuit58 of the light source device 3, to make a setting to obtain a state ofsupplying illumination light for normal light observation.

Further, the control circuit 47 controls to drive the driving circuit 45a and sets operation state of the signal processing circuit 46 to normallight observation mode.

The user inserts the insertion portion 11 of the endoscope 2 in the bodycavity, to make a setting so that a diseased part of the diagnosisobject can be observed.

The light source device 3 is brought into a state of supplyingillumination light for normal light observation as described above. Inthis state, the rotary filter 53 is rotationally driven by the motor 55,with the RGB filter located in an illumination optical path. Then, RGBillumination lights are supplied to the light guide 21 in a surfacesequential manner. Synchronously therewith, the driving circuit 45 aoutputs a driving signal to illuminate a diseased part or the like inthe body cavity of the patient through the three illumination lenses 25a, 25 b, 25 c.

The illuminated subject such as a diseased part is focused on a lightreceiving surface of the image pickup device 33 through the lens unit 32of the normal light image pickup unit 31A, and is subject tophotoelectric conversion. Then, the image pickup device 33, when appliedwith a driving signal, outputs photoelectrically converted signals. Thesignals are inputted to the signal processing circuit 46 via the signalcable 38 a and the common signal cable 43 selected by the relay board42.

The signals inputted to the signal processing circuit 46 are subject toA/D conversion therein, and thereafter temporarily stored in an RGBmemory.

Subsequently, the signals stored in the RGB memory are simultaneouslyread out into synchronized R, G, B signals, which are further D/Aconverted into analog R, G, B signals to be color displayed on themonitor 5.

If the user desires to inspect the diseased part in more detail byfluorescent light observation in addition to normal light observation,the user turns on the control switch 48 a. Then, on receiving theswitching instruction signal, the control circuit 47 performs switchingcontrol of the relay board 42, and sets the light source device 3 to astate of supplying excitation light for fluorescent light observationvia the control circuit 58.

The control circuit 47 also controls the driving circuit 45 b intooperation state, and sets the signal processing circuit 46 to aprocessing mode for fluorescent light observation.

In this case, the control circuit 58 in the light source device 3 causesthe gear-equipped motor 57 to move the rotary filter 53 along with themotor 5 in a direction orthogonal to an illumination optical path, sothat the excitation light filter is located in the illumination opticalpath.

In this state, light from the lamp 51 is transmitted by the excitationlight filter in a wavelength band of about, for example, 400 to 450 nm,to be supplied to the light guide 21. The excitation light is thenirradiated to a diseased part or the like in the body cavity, throughthe three illumination lenses 25 a, 25 b, 25 c.

When the diseased part or the like irradiated with the excitation lightis an abnormal region such as of carcinoma tissues, the part absorbs theexcitation light and emits fluorescent light stronger than in a case ofa normal organization. The light of the region emitting the fluorescentlight is focused on the light receiving surface of the image pickupdevice 38 through the lens unit 36 of the fluorescent light image pickupunit 31B, and then is subject to photoelectric conversion.

The image pickup device 38, when applied with a driving signal from thedriving circuit 45 b, outputs photoelectrically converted signals. Inthis case, the signals are amplified in the image pickup device 38 andthen outputted therefrom. The signals are inputted to the signalprocessing circuit 46 through the signal cable 38 b and the commonsignal cable 43 selected by the relay board 42.

The signals inputted into the signal processing circuit 46 are A/Dconverted therein, and then stored in the RGB memory, simultaneously,for example.

Thereafter, the signals stored in the RGB memory are simultaneously readout into synchronized R, G, B signals, which are further D/A convertedinto analog R, G, B signals to be displayed on the monitor 5 in a blackand white manner.

Note that the signals inputted into the signal processing circuit 46 maybe provided in pseudo colors and displayed by comparing the signals inlevel with a plurality of thresholds and changing colors to be assigneddepending on the comparison result.

Thus, the present embodiment, which is capable of performing the normallight observation as well as the fluorescent light observation, canrealize an endoscope facilitating diagnosis compared with an endoscopeonly for normal light observation. Moreover, the present embodiment,which is provided with the respective image pickup unit 31A, 31B, canobtain fine normal light observation images and special lightobservation images.

Specifically, when performing a fluorescent light image pickup inparticular, it is necessary to capture light weaker than in normalobservation: light preferably having a high signal to noise ratio. Inthis case, using a normal image pickup device for both observationseasily results in an image having low signal to noise ratio. However,the present embodiment can obtain a fluorescent light image with a goodsignal to noise ratio by adopting the image pickup device 38 suitablefor fluorescent light image pickup, which is more sensitive to lightrelative to the image pickup device 33 for normal observation.

Further, provided with the switching relay board 42 to connect only oneof the two image pickup units 31A, 31B to the processor 4, the endoscopesystem 1 can be formed to be more compact than when the two image pickupunit 31A, 31B each always has to be driven and signal processed.

Still further, the present embodiment can reduce diameter of theinsertion portion 11, relieve pain given to a patient in insertion, andexpand the insertable application area, because the single air/waterfeeding nozzle 60 is used to spray gas or liquid onto the outer surfacesof the both observation lenses 31 a, 31 b to set the surfaces to a cleanstate to allow securing good observation field of view.

Yet still further, the endoscope 2 of the present embodiment, having ansimilar exterior structure to that of an existing endoscope onlyincluding an image pickup unit for normal light observation, can also beused as an endoscope for normal light observation in a similar mannerwith an existing endoscope by connecting the endoscope 2 via the scopecable 44 to a processor not shown for driving and signal processing anexisting endoscope only including an image pickup unit for normal lightobservation. In other words, the endoscope 2 can also be used connectedto an existing processor, while maintaining compatibility similar tothat for the existing endoscope only including the image pickup unit fornormal light observation.

Here, the endoscope 2 of the present embodiment has variouscharacteristics (effects) owing to structures described below.

First, referring to FIGS. 12 and 13, there are described in detail,dispositions of the air/water feeding nozzle 60 and each of theobservation lenses 31 a, 31 b disposed on the distal end cover 24.

FIGS. 12 and 13 are front views each showing a distal end surface of thedistal end cover. Note that, in the following description, center of thedistal end cover 24 is denominated as O₀, center of the observation lens31 a of the normal light image pickup unit 31A as O₁, and center of theobservation lens 31 b of the fluorescent light image pickup unit 31B asO₂. Also, centers of the three illumination lenses 25 a, 25 b, 25 cdescribed below are respectively denominated as O₃, O₄, O₅, center ofthe aperture portion 26 of the treatment instrument channel 19 as O₆,and center of the aperture portion 27 of the forward water-feedingchannel 20 as O₇. Further, a line passing through the center O₀ of thedistal end surface of the distal end cover 24 and oriented in a bendingup/down direction of the bending portion 16 is denominated as aperpendicular line X, and a line in a bending left/right direction as ahorizontal line Y. Note that, in the following description, theperpendicular line X in the present embodiment is regarded as a lineequated with a plumb line.

As described above, the air/water feeding nozzle 60 is disposed on theupper left side on the distal end surface of the distal end cover 24 asviewed toward the surface of FIG. 12, such that the spouting port 60 aof the air/water feeding nozzle 60 faces the observation lens 31 a. Notethat, the air/water feeding nozzle 60 may also be disposed on the upperright side on the distal end surface of the distal end cover 24 asviewed toward the surface of FIG. 12, such that the spouting port 60 aof the air/water feeding nozzle 60 faces the observation lens 31 a. Atthis time, the air/water feeding nozzle 60 and each of the observationlenses 31 a, 31 b are located on the distal end surface of the distalend cover 24 so as to line up on a generally straight line.

In the present embodiment, the air/water feeding nozzle 60 is disposedon the distal end surface of the distal end cover 24 such that gas orliquid such as distilled water or air is spouted out from the spoutingport 60 a of the air/water feeding nozzle 60 in the direction of anarrow line AR in the drawing. The air/water feeding nozzle 60 spoutsout, in a spreading manner, the gas or liquid such as distilled water orair into a gas/liquid spouting area A from the spouting port 60 a. Notethat the arrow line AR is a line in a direction generally orthogonal tothe distal end surface of the air/water feeding nozzle 60 including thespouting port 60 a, and passing through the center of a hole surface ofthe spouting port 60 a.

Setting direction of the air/water feeding nozzle 60 about an axisthereof, that is, direction in which the spouting port 60 a faces, isdetermined such that an observation optical axis passing through thecenter O₁ of the observation lens 31 a intersects the above-describedarrow line AR. In other words, the direction in which spouting port 60 aof the air/water feeding nozzle 60 faces is determined such that thearrow line AR as the spouting direction of the gas or liquid such asdistilled water or air is in a predetermined angle θ as a first anglewith respect to the perpendicular line X.

On the other hand, the observation lens 31 b of the fluorescent lightimage pickup unit 31B is disposed on a lower right side on the distalend surface of the distal end cover 24 toward the surface of FIG. 10,such that an outer surface of the observation lens 31 b has a partintersecting at least the arrow line AR when the distal end cover 24 isviewed from a distal end thereof. The observation lens 31 b is alsodisposed on the distal end surface of the distal end cover 24 such thatthe center O₂ of the observation lens 31 b is located on a side lowerthan the line segment of the arrow line AR.

As described above, the air/water feeding nozzle 60 and the twoobservation lenses 31 a, 31 b are adjacently provided on the generallystraight line on the distal end surface of the distal end cover 24.

In detail, a line a linking the center O₁ of the observation lens 31 aof the normal light image pickup unit 31A and the center O₂ of theobservation lens 31 b of the fluorescent light image pickup unit 31B isslightly shifted toward a lower side when the distal end cover 24 isviewed from the distal end surface side thereof, with a predeterminedangle θ2 with respect to the arrow line AR. In other words, a line blinking the center of a hole surface of the spouting port 60 a of theair/water feeding nozzle 60 and the center O₂ of the observation lens 31b is slightly shifted toward an upper side when the distal end cover 24is viewed from the distal end surface side, with a predetermined angleθ3 with respect to the arrow line AR.

This determines respective disposition positions of the observationlenses 31 a, 31 b on the distal end cover 24. In line with thesepositions, direction of the spouting port 60 a of the air/water feedingnozzle 60 (direction of the arrow line AR) is determined. Further, theangles θ2, θ3 are set in ranges such that the gas/liquid spouting area Afrom the air/water feeding nozzle 60 includes the entire outer surfaceof the observation lens 31 b.

Note that the gas/liquid spouting area A of the air/water feeding nozzle60 is set to entirely include an outer surface of the observation lens31 a of the normal light image pickup unit 31A when viewed from thedistal end side of the distal end cover 24.

Also, the observation lens 31 a having a lens diameter (caliber) largerthan an outer diameter of the observation lens 31 b is disposed on thedistal end surface of the distal end cover 24, close to the air/waterfeeding nozzle 60.

That is, the distal end cover 24 has the air/water feeding nozzle 60 ata position on an upper side than the horizontal line Y generallybisecting the bending up/down direction of the bending portion 16 withrespect to a direction viewed from the distal end surface side, that is,up/down direction of the vertical transfer direction in which therespective image pickup devices 33, 38 included in the image pickupunits 31A, 31B perform processings. In other words, the air/waterfeeding nozzle 60 is disposed on the distal end cover 24, apart from thehorizontal line Y in an opposite direction from the spouting direction(arrow line AR direction).

Further, on the distal end cover 24, the air/water feeding nozzle 60 isdisposed such that a section surface in a direction orthogonal to alongitudinally directed axis of the air/water feeding nozzle 60 (axisparallel to the insertion direction) does not exist on the perpendicularline X which bisects a left/right direction (which is reverse to thebending left/right direction of the bending portion 16) relative to thedirection as viewed from the distal end surface side of the distal endcover, that is, left/right direction of the vertical transfer directionin which the image pickup devices 33, 38 included in the respectiveimage pickup units 31A, 31B perform processings.

Note that, in the present embodiment, the air/water feeding nozzle 60 isdisposed on a position on the distal end surface of the distal end cover24, so as to be apart from the perpendicular line X in a left directionby a predetermined distance, when viewed from the distal end surfaceside of the distal end cover 24. That is, the air/water feeding nozzle60 is located such that a longitudinal axis thereof is present at aposition which is on an upper side than the horizontal line Y bisectingthe distal end cover 24 into upper and lower sides and is shifted towardleft side from the perpendicular line X bisecting the distal end cover24 into right and left sides, when viewed from the distal end surfaceside of the distal end cover 24.

As a result of the foregoing, the endoscope 2 of the present embodimentcan be secured of a good observation field of view by using the singleair/water feeding nozzle 60 to spray gas or liquid onto the outersurfaces of the respective observation lenses 31 a, 31 b to set thesurfaces in a clean state, when the air/water feeding nozzle 60, theobservation lens 31 a of the normal light image pickup unit 31A, and theobservation lens 31 b of the fluorescent light image pickup unit 31Bprovided on the distal end surface of the distal end cover 24 arelocated on a generally straight line.

Also, the longitudinal axis of the air/water feeding nozzle 60 isshifted toward an upper side than the horizontal line Y bisecting thedistal end cover 24 to upper and lower sides, and by a predetermineddistance from the perpendicular line X bisecting the distal end cover 24to right and left sides. Therefore, when the insertion portion 11 is ina generally straight line, the air/water feeding duct 61 communicatingwith the air/water feeding nozzle 60 is generally straightly inserted inthrough the distal end portion 15 and the bending portion 16, withoutcoming into contact with the four fixing portions 18 a of the fixingring 18 disposed in the distal end portion 15 and the four wire guards 7a respectively provided on the bending pieces 7 disposed in the bendingportion 16.

Further, because the above-described disposition of the air/waterfeeding nozzle 60 prevents the air/water feeding duct 61 from cominginto contact in the bending portion 16 with the four bending operationwires 8 respectively inserted and held in the four wire guards 7 a ofeach of the bending pieces 7, movement of the bending operation wire 8due to pulling and relaxing is prevented from being obstructed, anddeterioration of the bending operation wire 8 due to scratch can beprevented.

As a result of the foregoing, the endoscope 2 of the present embodimentcan reduce the diameter of the insertion portion 11, particularly of thedistal end portion 15 and the bending portion 16, relieve pain given toa patient in insertion, and expand the insertable application area inthe body cavity.

In addition, the endoscope 2 is generally used with the bending up/downdirection of the bending portion 16 being adjusted to up/down directionof the plumb direction by the user. Therefore, liquid such as distilledwater spouted out from the spouting port 60 a of the air/water feedingnozzle 60 flows toward a lower side, on a side farther from the spoutingport 60 a, due to the effect of gravity.

Further, in a case where gas or liquid such as distilled water or air isspouted out from the spouting port 60 a of the air/water feeding nozzle60, and at the same time suction is performed through the treatmentinstrument channel 19, the liquid or gas is applied with a drawing forcetoward the aperture portion 26 due to the suction force from theaperture portion 26 of the treatment instrument channel 19 provided on alower side on distal end cover 24, and is thereby changed in flowdirection toward the bending lower side.

Under such circumstances, in the endoscope 2 of the present embodiment,the observation lens 31 b of the fluorescent light image pickup unit 31Bis located on the distal end surface of the distal end cover 24 suchthat the line a linking the center O₂ thereof with the center O₁ of theobservation lens 31 a of the normal light image pickup unit 31A isshifted by a predetermined angle θ2 toward the bending lower side of thebending portion 16 with respect to the arrow line AR which is thespouting direction of a liquid such as distilled water spouted out fromthe spouting port 60 a of the air/water feeding nozzle 60.

Accordingly, on the distal end surface of the distal end cover 24, theobservation lens 31 b positioned farther than the observation lens 31 afrom the air/water feeding nozzle 60 is efficiently sprayed with aliquid such as distilled water flowing down toward the bending lowerside than the spouting direction due to the effect of gravity. Theobservation lens 31 b is thus cleaned into a clean state and secured ofa good observation field of view. Further, the observation lens 31 b islikewise efficiently sprayed with gas or liquid such as distilled wateror air whose flow is changed to the bending lower side by suctionperformed, to be cleaned into a clean state and secured of a goodobservation field of view.

Furthermore, the endoscope 2 inserted in the body cavity of the patienthas the insertion portion 11 adhered with filth or the like. Inparticular, the distal end surface of the distal end cover 24, which isgenerally perpendicular to the insertion direction, is easily adheredwith filth or the like. The observation lens 31 a of the normal lightimage pickup unit 31A and the observation lens 31 b of the fluorescentlight image pickup unit 31B are especially required to be surely cleanedof adhering filth or the like in order to secure respective observationfields of view.

In particular, the endoscope 2 is required to secure better observationfield of view for the normal light observation than for the fluorescentlight observation in which tone of tissue pigments are observed, becausenormal light is more frequently used than the fluorescent lightobservation to observe a patient's body cavity.

Also, gas or liquid such as distilled water or air spouted out from thespouting port 60 a of the air/water feeding nozzle 60 has largerspouting force on the side closer to the spouting port 60 a. On afarther side in the spouting direction, the spouting force decreases anddensity of the gas or liquid also decreases due to spreading thereof.

Under such circumstances, in the endoscope 2 of the present embodiment,the observation lens 31 a of the normal light image pickup unit 31Ahaving a larger lens diameter (caliber) than that of the observationlens 31 b of the fluorescent light image capturing unit 31B is disposedat a position closer to the air/water feeding nozzle 60 on the distalend surface of the distal end cover 24, as shown in FIG. 11. Asdescribed above, the entire outer surface of the observation lens 31 ais included in the spouting area A of the gas or liquid such asdistilled water or air spouted out from the spouting port 60 a of theair/water feeding nozzle 60.

Thus, in the endoscope 2, the observation lens 31 a having a larger lensdiameter (caliber) easily adhered with body fluid, filth or the like iscloser to the air/water feeding nozzle 60, and accordingly, cleanabilityof the observation lens 31 a can be improved without being affected bydecrease of spouting force and density of gas or liquid such asdistilled water or air spouted out from the spouting port 60 a.

Note that as described above, the air/water feeding nozzle 60, theobservation lens 31 a of the normal light image pickup unit 31A, and theobservation lens 31 b of the fluorescent light image pickup unit 31B areadjacently provided on a generally straight line on the distal endsurface of the distal end cover 24 shown in FIG. 12, in the endoscope 2of the present embodiment. Further, on the arrow line AR which is thespouting direction of gas or liquid such as distilled water or air to bespouted out from the spouting port 60 a of the air/water feeding nozzle60, other component parts are not disposed on the distal end surface ofthe distal end cover 24.

That is, on the arrow line AR, other component parts are not disposed onan outer circumferential side on the distal end surface of the distalend cover 24 from the observation lens 31 b of the fluorescent lightimage pickup unit 31B.

With such a configuration, the gas or liquid that cleaned the filthadhering on each of the observation lenses 31 a, 31 b flows toward anouter edge portion of the distal end cover 24 in the arrow line ARdirection which is the spouting direction, without flowing to the othercomponent parts. As a result, when the gas or liquid such as distilledwater or air is spouted out from the air/water feeding nozzle 60, thedistal end surface of the distal end cover 24 of the endoscope 2 issurely cleaned.

Next, referring to FIGS. 12 and 13, dispositions of the aperture portion26 and 27 of the treatment instrument channel 19 and the forwardwater-feeding channel 20, respectively, disposed on the distal end cover24 are described in detail.

As described above, on the distal end surface of the distal end cover24, the aperture portion 26 of the treatment instrument channel 19 isdisposed at a position on a lower left side of the observation lens 31a, and the aperture portion 27 of the forward water-feeding channel 20is disposed at a position on an upper right side of the observation lens31 a.

As shown in FIG. 12, respective entire hole surfaces of the apertureportion 26 of the treatment instrument channel 19 and the apertureportion 27 of the forward water-feeding channel 20 are disposed on thedistal end surface of the distal end cover 24 which is outside thegas/liquid spouting area A which is an area in which gas or liquid suchas distilled water or air is spouted out in a spreading manner from thespouting port 60 a of the air/water feeding nozzle 60.

In detail, as shown in FIG. 13, the aperture portion 26 of the treatmentinstrument channel 19 is disposed in an area B in the distal end surfaceof distal end cover 24, which is an area on a lower side of the distalend surface of the distal end cover 24 bisected along the arrow line ARindicating the spouting direction of gas or liquid such as distilledwater or air from the spouting port 60 a of the air/water feeding nozzle60, and not including the spouting area A of the gas or liquid.

The aperture portion 27 of the forward water-feeding channel 20 isdisposed in an area C on the distal end surface of the distal end cover24, which is an area on an upper side of the distal end surface of thedistal end cover 24 bisected along the arrow line AR, and not includingthe spouting area A of the gas or liquid.

In other words, on the distal end surface of the distal end cover 24,the aperture portions 26, 27 are respectively disposed at positionsgenerally symmetric about the arrow line AR indicating the spoutingdirection of the gas or liquid such as distilled water or air. That is,the aperture portion 26, 27 are disposed on the distal end surface ofthe distal end cover 24 at a position where the center O₆ of theaperture portion 26 and the center O₇ of the aperture portion 27 areapart from each other by a predetermined distance.

As described above, the endoscope 2 of the present embodiment canprevent the gas or liquid such as distilled water or air spouted outfrom the air/water feeding nozzle 60 from flowing into the apertureportions 26, 27, because the aperture portion 26 of the treatmentinstrument channel 19 and the aperture portion 27 of the forwardwater-feeding channel 20 are disposed in an area outside the gas/liquidspouting area A by the air/water feeding nozzle 60 on the distal endsurface of the distal end cover 24.

This allows the gas or liquid such as distilled water or air spouted outfrom the air/water feeding nozzle 60 to be surely sprayed onto theobservation lens 31 b of the fluorescent light image pickup unit 31B ona farther side. As a result, the observation lens 31 b of thefluorescent light image pickup unit 31B is surely and efficientlysprayed with the gas or liquid to be cleaned into a clean state, thussecuring a good observation field of view.

Also, the aperture portion 26, 27 are disposed on the distal end surfaceof the distal end cover 24 such that the respective centers O₆, O₇ areapart from each other by a predetermined distance. This allows theendoscope 2 to spout out a liquid toward a diseased part in the bodycavity, without being affected by the suction force to the apertureportion 26, when spouting out a liquid such as distilled water from theaperture portion 27 of the forward water-feeding channel 20 whileperforming sucking action from the aperture portion 26 through thetreatment instrument channel 19. That is, the endoscope 2 of the presentembodiment is configured to prevent the spouting direction of the liquidspouted out from the aperture portion 27 from being disturbed by thesucking from the aperture portion 26.

Next, referring to FIGS. 12 to 14, locations of the three illuminationlenses 25 a, 25 b, 25 c disposed on the distal end cover 24 aredescribed in detail. FIG. 14 is a plan view showing the distal end coveras viewed from the front.

As described above, on the distal end surface of the distal end cover24, the illumination lenses 25 a, 25 b are disposed at a position in thebending left/right direction in a manner sandwiching the observationlens 31 a of the normal light image pickup unit 31A disposed at thegenerally center, and the illumination lenses 25 a, 25 c are disposed ata position in the bending up/down direction in manner sandwiching theobservation lens 31 b of the fluorescent light image pickup unit 31B.

By this, enough amount of illumination light is irradiated on a regionto be inspected by the at least two illumination lens 25 a, 25 bsandwiching the observation lens 31 a in photographing by the normallight image pickup unit 31A. The outer surface of the illumination lens25 a is located in the spouting area A for liquid or gas from theair/water feeding nozzle 60.

Therefore, even when adhered with mucous membrane, blood, filth or thelike in the body cavity, the outer surface of the illumination lens 25 ais sprayed with gas or liquid from the air/water feeding nozzle 60 to bebrought into a clean state. As a result, in the endoscope 2 of thepresent embodiment, an amount of illumination light not obstructing theobservation performance of the normal light image pickup unit 31A can beirradiated to the region to be inspected at least from the illuminationlens 25 a.

On the other hand, in photographing by the fluorescent light imagepickup unit 31B, enough amount of illumination light is irradiated tothe region to be inspected by at least the two illumination lens 25 a,25 c sandwiching the observation lens 3 lb. The two illumination lens 25a, 25 c have respective outer surfaces positioned in the spouting area Afor liquid or gas from the air/water feeding nozzle 60.

Therefore, even when adhered with mucous membrane blood, filth or thelike in the body cavity, the respective outer surfaces of the twoillumination lens 25 a, 25 c are sprayed with gas or liquid from theair/water feeding nozzle 60 to be brought into a clean state.

As a result, in fluorescent light observation, when there is a lesionregion in a diseased part, the fluorescent light image pickup unit 31Bcan receive the small amount of fluorescent light emitted from thelesion region, by means of the illumination light irradiated from atleast the two illumination lens 25 a, 25 c. Thus, in the endoscope 2 ofthe present embodiment, illumination light in an amount not obstructingthe observation performance of the fluorescent light image pickup unit31B can be irradiated to the region to be inspected from at least fromthe two illumination lens 25 a, 25 c.

Further, as shown in FIG. 14, the two observation lenses 31 a, 31 b arelocated in a contour region D which is a part in which respectivecenters O₁, O₂ of the lenses are surrounded by outer circumferences ofthe three illumination lenses 25 a to 25 c. Thus, enough photographinglight is made incident on each of the observation lenses 31 a, 31 b bydistribution of illumination light from the three illumination lenses 25a to 25 c in normal light observation or fluorescent light observation.

As a result, the endoscope 2 of the present embodiment is improved inobservability in the body cavity where almost no natural light enters inboth normal light observation and fluorescent light observation.

In the endoscope 2 of the present embodiment having the above-mentionedvarious characteristics (effects), the air/water feeding nozzle 60provided on the distal end surface of the distal end cover 24, theobservation lens 31 a of the normal light image pickup unit 31A, and theobservation lens 31 b of the fluorescent light image capturing unit 31Bare located on a generally straight line. Thus, by means of the singleair/water feeding nozzle 60, the outer surfaces of the observationlenses 31 a, 31 b are sprayed with gas or liquid to be set in a cleanstate, thus secured of good observation field of view. Also, theendoscope 2 can show enough observation performance by means of thethree illumination lenses 25 a, 25 b, 25 c provided on the distal endsurface of the distal end cover 24 in either of the normal lightobservation and the fluorescent light observation.

Note that as shown in FIG. 15, the observation lens 31 b of thefluorescent light image pickup unit 31B may be located at the generallycenter of the distal end surface of the distal end cover 24, and theobservation lens 31 a of the normal light image pickup unit 31A on anouter circumferential side of the distal end surface of the distal endcover 24. In such a configuration, the two illumination lens 25 a, 25 bare disposed in a manner sandwiching the observation lens 31 b on thedistal end surface of the distal end cover 24.

By this, in fluorescent light observation by the fluorescent light imagepickup unit 31B, illumination light including a specific wavelength bandis irradiated to a region to be inspected from the two illuminationlenses 25 a, 25 b, so that the fluorescent light image pickup unit 31Bcan receive through the observation lens 31 b an enough amount offluorescent light emitted from the region to be inspected. Accordingly,by means of the two illumination lenses 25 a, 25 b, the endoscope 2 canin particular ensure a good amount of observation light incident on thefluorescent light image pickup unit 31B that is required to be receivedin as large an amount as possible, and show enough observationperformance of the fluorescent light image pickup unit 31B.

Note that the special light observation may be not only the fluorescentlight observation but also that using a magnification optical systemwith a magnification of histological observation level (preferably notless than 100 times level) such as for cells and gland structure.

Furthermore, the present invention is not limited only to theabove-described embodiment, but may be variously modified withoutdeparting from the spirit and scope of the invention.

1. An endoscope insertion portion comprising: a distal end portion; first image pickup means for obtaining a first observation image, the first image pickup means being disposed to the distal end portion; second image pickup means for obtaining a second observation image, the second image pickup means being disposed to the distal end portion; a first object optical system for condensing photographing light incident on the first image pickup means, the first object optical system being located in the distal end portion; a second object optical system for condensing photographing light incident on the second image pickup means, the second object optical system being located in the distal end portion; and a plurality of illumination optical systems for irradiating light to a subject, the plurality of illumination optical systems being located in the distal end portion in a manner sandwiching each of the first object optical system and the second object optical system.
 2. The endoscope insertion portion according to claim 1, wherein the plurality of illumination optical systems are three illumination optical systems formed of a first illumination optical system, a second illumination optical system, and a third illumination optical system, and the first and second illumination optical systems are located in a manner sandwiching the first object optical system, and the first and third illumination optical systems are located in a manner sandwiching the second illumination optical system, on the distal end portion.
 3. The endoscope insertion portion according to claim 2, wherein respective centers of the first object optical system and the second object optical system are located in a contour area that is surrounded by outer circumferences of the first illumination optical system, the second illumination optical system, and the third illumination optical system.
 4. The endoscope insertion portion according to claim 1, wherein the first image pickup means obtains a normal light observation image as a first observation image, and the second image pickup means obtains a special light observation image as a second observation image.
 5. The endoscope insertion portion according to claim 4, wherein the plurality of illumination optical systems are each located in the distal end portion in a manner sandwiching at least the second object optical system for obtaining the special light observation image.
 6. The endoscope insertion portion according to claim 5, wherein the special light observation image is a fluorescent light observation image.
 7. The endoscope insertion portion according to claim 1, wherein one of the first and second object optical systems has a magnification higher than that of the other.
 8. The endoscope insertion portion according to claim 2, wherein the first image pickup means obtains a normal light observation image as a first observation image, and the second image pickup means obtains a special light observation image as a second observation image.
 9. The endoscope insertion portion according to claim 3, wherein the first image pickup means obtains a normal light observation image as a first observation image, and the second image pickup means obtains a special light observation image as a second observation image.
 10. The endoscope insertion portion according to claim 8, wherein the plurality of illumination optical systems are each located in the distal end portion in a manner sandwiching at least the second object optical system for obtaining the special light observation image.
 11. The endoscope insertion portion according to claim 9, wherein the plurality of illumination optical systems are each located in the distal end portion in a manner sandwiching at least the second object optical system for obtaining the special light observation image.
 12. The endoscope insertion portion according to claim 10, wherein the special light observation image is a fluorescent light observation image.
 13. The endoscope insertion portion according to claim 11, wherein the special light observation image is a fluorescent light observation image.
 14. The endoscope insertion portion according to claim 2, wherein one of the first and second object optical systems has a magnification higher than that of the other.
 15. The endoscope insertion portion according to claim 3, wherein one of the first and second object optical systems has a magnification higher than that of the other.
 16. The endoscope insertion portion according to claim 4, wherein one of the first and second object optical systems has a magnification higher than that of the other.
 17. The endoscope insertion portion according to claim 5, wherein one of the first and second object optical systems has a magnification higher than that of the other.
 18. The endoscope insertion portion according to claim 6, wherein one of the first and second object optical systems has a magnification higher than that of the other. 